Incomplete conversion for the MySQL query

int MySQLDatabase::GetTableId(const std::wstring &UNUSED(catalog), const std::wstring &schema, const std::wstring &table, long &id, std::vector<std::wstring> &errors) { printf( "Schema in GetTableId is: %s\n\r", m_pimpl->m_myconv.to_bytes( schema.c_str() ).c_str() ); std::wstring query1 = L"SELECT st.table_id FROM information_schema.tables t, information_schema.innodb_tables st WHERE st.name = CONCAT(t.table_schema,'/',t.table_name) AND t.table_schema = ? AND t.table_name = ? AND t.engine = 'InnoDB';"; int result = 0; long tableId = 0; unsigned long str_length1 = 0, str_length2 = 0; MYSQL_RES *prepare_meta_result = nullptr; auto res1 = mysql_stmt_init( m_db ); if( !res1 ) { std::wstring err = m_pimpl->m_myconv.from_bytes( mysql_stmt_error( res1 ) ); errors.push_back( err ); result = 1; } if( !result ) { if( mysql_stmt_prepare( res1, m_pimpl->m_myconv.to_bytes( query1.c_str() ).c_str(), query1.length() ) ) { std::wstring err = m_pimpl->m_myconv.from_bytes( mysql_stmt_error( res1 ) ); errors.push_back( err ); result = 1; } } if( !result ) { MYSQL_BIND params[2]; memset( params, 0, sizeof( params ) ); str_length1 = strlen( m_pimpl->m_myconv.to_bytes( schema.c_str() ).c_str() ) + 1; str_length2 = strlen( m_pimpl->m_myconv.to_bytes( table.c_str() ).c_str() ) + 1; std::unique_ptr<char[]> str_data1( new char[str_length1] ); std::unique_ptr<char[]> str_data2( new char[str_length2] ); memset( str_data1.get(), '\0', str_length1 ); memset( str_data2.get(), '\0', str_length2 ); snprintf( str_data1.get(), str_length1, "%s", m_pimpl->m_myconv.to_bytes( schema.c_str() ).c_str() ); snprintf( str_data2.get(), str_length2, "%s", m_pimpl->m_myconv.to_bytes( table.c_str() ).c_str() ); params[0].buffer_type = MYSQL_TYPE_STRING; params[0].buffer = (char *) str_data1.get(); params[0].buffer_length = str_length1 - 1; params[0].is_null = 0; params[0].length = &str_length1 - 1; params[1].buffer_type = MYSQL_TYPE_STRING; params[1].buffer = (char *) str_data2.get(); params[1].buffer_length = str_length2 - 1; params[1].is_null = 0; params[1].length = &str_length2 - 1; if( mysql_stmt_bind_param( res1, params ) ) { std::wstring err = m_pimpl->m_myconv.from_bytes( mysql_stmt_error( res1 ) ); errors.push_back( err ); result = 1; } if( !result ) { if( mysql_stmt_execute( res1 ) ) { std::wstring err = m_pimpl->m_myconv.from_bytes( mysql_stmt_error( res1 ) ); errors.push_back( err ); result = 1; } } if( !result ) { prepare_meta_result = mysql_stmt_result_metadata( res1 ); if( !prepare_meta_result ) { std::wstring err = m_pimpl->m_myconv.from_bytes( mysql_stmt_error( res1 ) ); errors.push_back( err ); result = 1; } } } if( !result ) { MYSQL_BIND results1[1]; bool is_null[1], error[1]; unsigned long length[1]; memset( results1, 0, sizeof( results1 ) ); results1[0].buffer_type = MYSQL_TYPE_LONG; results1[0].buffer = (char *) &tableId; results1[0].is_null = &is_null[0]; results1[0].error = &error[0]; results1[0].length = &length[0]; if( mysql_stmt_bind_result( res1, results1 ) ) { std::wstring err = m_pimpl->m_myconv.from_bytes( mysql_stmt_error( res1 ) ); errors.push_back( err ); result = 1; } if( !result ) { if( mysql_stmt_store_result( res1 ) ) { std::wstring err = m_pimpl->m_myconv.from_bytes( mysql_stmt_error( res1 ) ); errors.push_back( err ); result = 1; } } auto rows = mysql_stmt_num_rows( res1 ); if( !result ) { auto fetch = mysql_stmt_fetch( res1 ); switch( fetch ) { case 1: { std::wstring err = m_pimpl->m_myconv.from_bytes( mysql_stmt_error( res1 ) ); errors.push_back( err ); result = 1; } break; case 0: printf( "Table id is: %ld", tableId ); id = tableId; break; case MYSQL_NO_DATA: break; case MYSQL_DATA_TRUNCATED: errors.push_back( L"Data truncated" ); break; } } mysql_free_result( prepare_meta_result ); } if( !result ) { if( mysql_stmt_close( res1 ) ) { std::wstring err = m_pimpl->m_myconv.from_bytes( mysql_stmt_error( res1 ) ); errors.push_back( err ); result = 1; } } return result; }

I'm getting 0 in the id parameter, so I added couple of printf's in that function.

The first printf does print my schema name when I run that code.

Next I turned on logging on the MySQL.

And the log shows:

12 Execute SELECT st.table_id FROM information_schema.tables t, information_schema.innodb_tables st WHERE st.name = CONCAT(t.table_schema,'/',t.table_name) AND t.table_schema = '' AND t.table_name = 'league' AND t.engine = 'InnoDB'.

How can it be? The second parameter converts fine with the same code, but not the first one. Please explain this.

MySQL version is 8.0.32. MySQL-connector version is 8.0.32.